1. Field of the Invention
This invention relates to a method of authentication, a contents-information sender apparatus, a contents-information receiver apparatus, and an authentication system.
2. Description of the Related Art
According to a typical method of protecting the copyright on contents during the transmission thereof, a sender encrypts information representative of the contents and transmits the encryption-resultant contents information to a receiver. To enhance the ability to protect the copyright, authentication is implemented. Specifically, the receiver transmits its own ID (identification) signal to the sender. The sender decides whether the receiver is legitimate or illegal by referring to the ID signal transmitted from the receiver. When the receiver is decided to be legitimate, the sender executes the transmission of the encryption-resultant contents information to the receiver. On the other hand, when the receiver is decided to be illegal, the sender does not transmit the encryption-resultant contents information to the receiver.
In the case where an illegal receiver transmits a correct ID signal to the sender, the encryption-resultant contents information is transmitted from the sender to the illegal receiver. If the encryption-resultant contents information received by the illegal receiver is successfully decrypted, the copyright on the contents will be infringed.